The University of Washington (UW) Clinical Center has been a significant contributor in the LABS Consortium since its inception and currently recruits subjects for LABS2 study from two Seattle-area hospitals performing bariatric operations: the University of Washington Medical Center (UWMC) and Virginia Mason Medical Center (VMMC). We propose to complete LABS2 recruitment at the UW Clinical Center by 6/30/2009 and to extend longitudinal follow-up of the LABS2 cohort through 6/30/2014. As the second highest Clinical Center contributor to LABS2 surgeries, we anticipate follow-up of 520 LABS2 subjects annually. An observational, longitudinal study innately involves retention challenges and to address these challenges, we propose a rigorous retention plan and study management plan to track and follow-up with subjects enrolled at the UW Clinical Center. Continuing participation of the UW Clinical Center will significantly contribute to achieving LABS consortium stated aims: Specific Aim 1: Effectively retain subjects to complete the longitudinal, observational cohort database. Specific Aim 2: Complete the comprehensive LABS database and disseminate the LABS results to the medical and scientific communities. Specific Aim 3: Examine serial changes in biological outcomes (i.e. C-reactive protein, creatinine) in relation to weight loss and change in comorbidities. Specific Aim 4: Maintain the infrastructure to support the conduct and analysis of ancillary studies funded through external mechanisms. RELEVANCE (See instructions): The LABS Consohtum is a well-developed research infrastructure that includes heterogeneous cohorts of bariatric surgery patients. Longer term follow-up will enable examination of the relationship between surgery and variable weight loss and regain of weight to clinical responses, the durability of the weight loss and the improvements in comorbidity responses, and examine post-surgical outcomes that evolve over time.